Powder dispensing device



. May 1 1964 E. L. ZEHRBACH POWDER DISPENSING DEVICE Filed March 14, 1962 FIGI.

United States Patent 3,132,769 PGWDER DISPENSING DEVICE.

Edgar L. Zehrbach, Mansfield, Ohio, assignor to Westinghouse Electric Corporation, East Pittsburgh, Pa, a corporation of Pennsylvania Filed Mar. 14, 1962, Ser. No. 17?,814

1 Claim. (Cl. 222-70) This invention relates to a powder dispensing device, especially for dispensing a powder which has pronounced bridging characteristics, such as diatomaceous earth and particularly a product thereof known as Diatomite which is extensively used in dry cleaning machines, and has for an object the provision of a dispensing device which will accurately dispense measured quantities of such powder without clogging up in spite of the bridging tendency of the powder. The term bridging is understood to mean the tendency of a powder to build up in an arch over a void. This is a kind of self-packing effect which is characteristic of certain materials.

Diatomite is one of the best known filtering agents for entrapping mechanical particles and is extensively used in dry cleaning machines for removing soiling substances from the dry cleaning fluid. It is usual to keep a dry cleaning machine in operation for a number of batches 3,132,769 Patented May 12, 1964 "ice - only to know that the powder gets into the liquid in the of materials or goods (usually clothing) between changes of dry cleaning fluid; and the cleaning fluid is kept in circulation at all times, even between batch cleanings.

It has been found that best results with the use of a minimum amount of filter powder are produced by introducing an initial quantity or batch of powder when fresh cleaning fiuidis put into the machine and thereafter adding an additional quantity or batch of powder for each batch cleaning operation until fresh cleaning fluid is again added.

Dispensers for adding batches or charges of filter powder have been provided for dry cleaning machines but they have been unsatisfactory because they did not dispense accurate quantities or because they clogged up due to the bridging effect and stopped supplying powder altogether.

The'device provided by the present invention has been developed for use with dry cleaning machines and has been found to give excellent performance in this service, hence will be disclosed in connection with this particular use but with the understanding that it has other uses.

The invention also provides means for assuring that the dispensing openings will never be left in registry when the operation is stopped, whereby to avoid the flow of materials except when wanted.

The objects of the invention as well as certain novel features and advantages will be apparent from the following description of an exemplary embodiment thereof, reference being made to the accompanying drawings, where- FIG. 1 is a side elevation, partly cut away, of a dry cleaning machine installation having a filter powder dispenser embodying the invention;

FIG. 2 is an enlarged shortened vertical section an elevation of the dispenser;

tub and is conveyed by the liquid to the filter unit 16.

v The dispenser 20 includes a container, preferably barrel-shaped, comprising a bottom 22 and a side or cylindrical wall 24. 'It is to be particularly noted that the bottom 22 is inclined at an angle to the horizontal. This is preferably effected by inclining the entire container, thereby utilizing a container having its axis or center line disposed at right angles to the plane of the bottom, both being inclined at the same angle relative to the vertical and horizontal, respectively. In its lowermost portion, or adjacent its lower edge, the bottom 22 is provided with a discharge opening 23, which is preferably of a truncated sector shape, as shown in FIG. 3.

Many forms of dispensing machines, with various forms of stirrers and the like, were tried without success until it was found that this inclined arrangement would give satisfactory operation. Indeed, it has'been found that the angle itself is critical. Best results are achieved when the angle of inclination of the plane of the dispenser bottom relative to a horizontal plane is about thirty degrees (30) but reasonably good results are obtained with departures of about ten degrees (10)from this optimum inclination, that is, from about twenty degrees (20) to about forty degrees (40).

A rotating dispensing plate 28 is mounted on a shaft 29 passing at right angles through the center of thebottom so as to be located parallel to and very near the bottom and to rotate above the bottom, the plate having a plurality of dispensing openings30, here, two, which have a truncated sector shape of about the same size as the discharge opening 23, as shown in FIG. 3, and which move past, or into and out of registry with, the discharge opening 23 in the bottom of the container as the plate 28 rotates. The plate 28 is spaced by a working clearance, say about above the bottom of the container.

The shaft 29 is driven by a motor M through a gear train unit 31. The shaft turnrs rather slowly and, asan example, may deliver a total batch of eight to ten unit charges at the beginning of each batch cleaning cycle.

FIG. 3 is a transverse section takenon the line 3--3 As an example of dimensions which have been found to be satisfactory operation, the container is about 6" in diameter and about 12" high,;the dispenser plate about 5% diameter, and the openings about 1 /2" in radial length, 2%" outer width and about 1" inner width. Another important aspect of'successful operation for delivering accurate charges at all stages of filling of the dispensing container is that one or more stirring rods 32 are carried by the rotating plate 28 behind one or more openings. As shown here, the rod is located near the outer periphery of the dispensing plate, where it will Isweep material from the side wall of the container. While stirring rods alone have been used with other dispensers, they have been found to give special advantages when used in combination with other elements herein provided. They are especially helpful in securing the delivery of uniform amounts of material for different stages of filling of the container between completely full and almost empty.

Also an important aspect is the provision of narrow turned-up flanges 33 at the radially transverse trailing edges of the openings, reference being made to the direction of rotation of the dispensing plate as shown by the anrow in FIG. 3. The direction shown here is clockwise. In one form which has operated well, the flange is about 1" to 7 wide and about 1 /2" long.

A timer 43, which maybe of a conventional, well- I known type, controls the operation of the dry cleaner in accordance with the desired cycle of operation. ,It includes a pair of contacts controlling the supply of current'to the motor M, which contacts are closed during each automatic cycle or" operation for a period of time providing the desired number of unit charges of powder. However, the present invention provides means for assuring that the dispenser plate 28 will be stopped in. a position where neither of its openings 30 will register at all with the bottom discharge opening 23 of the container. As shown in FIGS. 2, 3 and 5, the shaft 29 is provided with a cam 40 having lobes 41 and, as shown in FIG. 5, a switch 42 of the leaf spring type has one blade located in a position where it is operated by the cam lobes as the shaft rotates. The lobes 41 are angularly' located on the shaft 29 so as to close the switch as long as either opening 30 is in partial or complete registry with the discharge opening 23. Each lobe 41 has an angular extent which is approximately twice the angular extent of one of the mentioned openings, in ordento close the switch during both the movement into'registry and the movement out of registry. The switch 42 is connected in parallel or shunt with the contacts in the timer 43 that control the dispenser motor M. Thus, should the timer contacts happen to open during the time that one of the openings 30 is in complete or partial registry with the discharge opening 23, the switch 42 will maintain the circuit closed and energize the motor to rotate the plate 28 until the openings are out of registry, whereupon the switch 42 will open and permit the plate 28 to stop. This assures that the dispenser plate will not be stopped with either of the openings 30 of the plate in registry with the opening 23 of the container.

In operation, the dispensing container is filled with powder by an attendant as often as is necessary, say,

once a day or once for each change or addition of cleaning fluid. At that time an initial batch of powder is put into the tub in addition to that used to fill the dispensing container. Thereafter, each time a batch of goods is put into the machine and the timing mechanism started, the dispenser will be operated for a predetermined length of time to introduce the desired number of measured f opening 39 of the plate is in registry with the discharge opening 23, a charge of powder will drop out, but since the material has a bridging tendency it will form an arch over the opening. The edge flange 33 and the rod 32 break down this arch as they move forward and leave the powder in a continuous body above the dispensing plate ready for the next dispensing action. The rod 32 is especially useful in keeping the dispensing action uniform in various stages of filling of the container.

Due to the inclination of the dispenser bottom and the dispenser plate, the amount of powder dispensed each time will be substantially the same. The raised leading edge flanges of the solid plate material behind each dispensing opening and the stirring rod (or rods) 32 aid in this action, particularly in regard to difierent degrees of filling of the container. If the powder starts to bridge, the inclined arrangement will tend to cause it to break up and slide down over the rotating dispensing plate tothe discharge opening, the stirrer 32 and the raised flange of the dispenser plate aiding in loosening material so it will flow down and fill the voids.

It is thus seen that the invention provides .a simple, inexpensive, accurate, and dependable-dispenser for powdered materials which have a bridging tendency.

While one embodiment of the invention has been described for purposes of illustration, it is to be understood that there may be various embodiments and modifications within the general scope of the invention.

What is claimed is:

A powder dispensing device comprising in combination,

a powder container provided with a bottom having a discharge opening therein,

a dispensing plate mounted for rotation above said bottom and having a dispensing opening located in a position to move into and out of registry with said discharge opening,

a motor connected to said plate for rotating said plate,

an electrical circuit connected to said motor for conducting electrical energy to said motor,

a timer in said circuit in series with said motor for ene-ngizing said motor for a predetermined period of time, and

means for maintaining energization of said motor while a dispensing opening is disposed in complete or partial'registry with said discharge opening, said lastmentioned means comprising means shunting said timer,

a switch in said shunting means adapted to effect energization of said motor independently of said timer, and

a cam lobe movable with said dispensing plate and formed to move said switch to motor energizing position during that portion of the movement of the dispensing plate in which its dispensing opening is in partial or complete registry with said discharge opening.

References Cited in the file of this patent UNITEDSTATES PATENTS Reynolds et al. July 31, 1962 

